By Andrew Tangel and Alison Sider
When a Boeing 777's engine cover broke apart and rained parts on
a Denver suburb on Feb. 20, the news rang familiar to Christopher
Behnam. In February 2018, the 777 he was piloting as captain
suffered a similar emergency with the same engine type.
His plane, United Airlines Flight 1175 to Honolulu, was over the
ocean 120 miles from the runway carrying more than 370 passengers
and crew when a violent blast rocked it.
The jet shook uncontrollably, rolled sharply, and the noise was
deafening, said Capt. Behnam. An engine had suffered severe damage.
Years of training kicked in, the pilots regained control and shut
the engine down. Even so, the plane was hard to handle. A third
pilot went into the cabin and looked out the window: The engine
hadn't just failed; its cover had ripped away.
"After the explosion, it felt like she was going to fall apart,"
Capt. Behnam said. "I knew I could fly the airplane. The issue was,
can I fly it long enough to land it?" The pilots brought the plane
to a safe landing in Hawaii.
The National Transportation Safety Board, which investigates
U.S. aviation failures, concluded that a roughly 35-pound fan blade
broke in the plane's Pratt & Whitney PW4000 engine due to
fatigue, spiraling forward and causing parts of the engine cover to
drop into the sea.
Until last month's Colorado incident involving United Flight
328, the aviation industry and the Federal Aviation Administration
had acted only haltingly to address such breakups. That's despite a
series of such failures starting at least five years ago.
Engine "fan blade-outs" are an old problem in aviation. But in
recent cases involving Boeing airliners, fast-spinning blade
fragments have shot forward into the engine's inlet, rather than
into a protective casing that acts like a bulletproof vest around
the sides.
That has resulted in another problem. Engine covers sometimes
aren't surviving those blade fractures, creating bigger hazards for
planes, passengers and people on the ground.
A similar engine-cover emergency had hit a Southwest Airlines
Co. Boeing 737 flight in 2016. At least three more happened after
Capt. Behnam's flight. Two months after his scare, a Southwest
engine cover broke and blasted out a window; a passenger was
partially sucked out and died. On Dec. 4, 2020, an engine broke up
on a 777 flight near Japan.
Regulators, engine makers and airlines have confronted the
problem with a short-term remedy. With varying degrees of urgency
in recent years, they have stepped up fan-blade inspections to find
pre-fracture cracks that could lead to engine covers ripping
off.
Despite working on modifications and replacements for more than
two years, plane maker Boeing Co., which is responsible for engine
coverings on its aircraft, and the FAA have yet to finalize plans
to redesign the types of engine covers that have ripped off. "We've
already seen extreme cases," said NTSB Chairman Robert Sumwalt. "It
is something that the industry needs to get on top of and get
corrected immediately."
Complicating the industry's response to the safety hazard is
that it requires coordination among several segments -- airplane
manufacturers, engine makers, airlines -- and among different
engineers and regulators focused on avoiding fan-blade fractures
and still others focused on preventing engine covers from detaching
midair.
In the U.S., that puts the FAA in the best position to tackle
the hazard. Its handling of the engine breakups is the regulator's
first big test since its fumbled responses to fatal Boeing 737 MAX
crashes in 2018 and 2019.
The FAA declined to make senior agency officials available for
interviews. A spokesman said a priority has been reducing the risk
of fan-blade failures that can lead to engine covers detaching
midair. The FAA spokesman said design changes to a "critical piece
of structure must be carefully evaluated and tested" to ensure they
provide the same level of safety or better without introducing
unintended risks.
Boeing spokesman Bradley Akubuiro said the company "has taken
steps to move forward" with the FAA to improve engine covers and is
giving its technical teams time they need to ensure any of the
manufacturer's design changes provide their expected performance
and maintain overall safety. While designing changes is "exacting
and time-consuming," he said, "this work has been, and remains, a
high priority."
Southwest spokeswoman Brandy King said the airline's leaders,
including Chief Executive Gary Kelly, were focused on understanding
and learning from the carrier's fatal accident while working with
manufacturers to prevent similar tragedies in the future. Pratt
& Whitney and United Airlines Holdings Inc. declined to
comment.
Planes made by Airbus SE haven't experienced any such
engine-cover breakups due to fan-blade fractures in recent years,
according to the European Union Aviation Safety Agency, the primary
regulator for Boeing's rival across the Atlantic.
Over the past five years, the problem of engine covers detaching
due to fan-blade failures that spew parts forward appears to have
primarily surfaced on two Boeing aircraft types, the 777 and 737,
which use engines made by different manufacturers, according to
current and former FAA officials.
To keep fan blades from breaking in the first place, regulators
have focused first on stepping up inspections. Within days of the
Dec. 4 engine breakup near Japan, Tokyo's air-safety regulators
ordered new engine inspections -- visual checks and
ultraviolet-light tests, a Japanese aviation official said.
The FAA opted against immediate action and was still considering
its next step when the United 777's engine broke apart near Denver
last month. Before that incident, Pratt & Whitney, a unit of
Raytheon Technologies Corp., was considering issuing a service
bulletin telling airlines to conduct specialized inspections of
certain 777 engines every 1,000 flights, said the NTSB's Mr.
Sumwalt. The FAA had required the deep inspections every 6,500
flights after the 2018 incident in Hawaii.
The FAA declined to comment about its response to the December
breakup. The agency said it makes safety-oversight decisions in a
rigorous, well-established analytical process aimed at quickly
identifying and mitigating risk, adding: "To suggest that there is
commonality among different events ignores the fact that data for
different events is unique to each specific event."
Early warning
An early warning about the risk that engine covers could crumble
when broken blades fly far enough forward came in August 2016. A
Southwest flight from New Orleans to Orlando made an emergency
landing after an engine failed -- a fan blade broke, causing
significant damage and leading the cabin to depressurize. One of
the engine's 24 fan blades had broken due to fatigue, NTSB
investigators found.
The spinning blade had careened into the front inlet where air
flows into the engine. Most of the inlet broke off, spitting debris
into the Boeing 737 jet's fuselage, wing and horizontal
stabilizer.
Regulators and industry experts, including at the NTSB,
generally viewed that event as a one-off, the NTSB's Mr. Sumwalt
said.
The engine's manufacturer, CFM International -- a joint venture
of General Electric Co. and France's Safran SA -- developed a new,
more high-tech inspection protocol using ultrasound technology. A
GE spokesman speaking on behalf of the joint venture said the
engine maker worked with regulators and customers to enhance and
implement inspection procedures and remained committed to working
on changes stemming from the NTSB's recommendations.
The FAA in 2017 considered mandating additional fan-blade
testing, though it didn't require additional checks until the
following year when it ordered emergency inspections in the
aftermath of the fatal engine-cover breakup on another Southwest
flight.
"We determined early that we would require some corrective
action and that it was an unsafe condition," Christopher Spinney,
an FAA engine specialist, said during an NTSB hearing in 2018. "But
we also determined that we had some time." Mr. Spinney, through an
FAA spokesman, declined to comment.
On Capt. Behnam's flight that year, after the fan blade
scattered parts of the 777's engine cover, the plane's aerodynamics
were out of whack. It felt, he said, like "having an open barn
door" on the right side of the plane.
Two months later on a Southwest 737, debris from an engine
covering -- again loosened by a broken fan blade -- smashed into
the plane's body, blasting out the window through which the
passenger was partially sucked.
She was the first U.S. airline-passenger fatality in nearly a
decade and Southwest's first passenger fatality. After the death,
Mr. Kelly, Southwest's CEO, pushed Boeing for an engine-cover fix
to avoid a repeat of such a tragedy, according to a person familiar
with the plane maker's work on the 737 engine cover.
After those incidents, the industry began to grapple with
vulnerable engine covers. Not only were fan blades failing, they
were doing damage to engine coverings that had been expected to
withstand such events.
Boeing engineers were particularly concerned about a potential
loss of control should engine covers break off and damage a plane's
horizontal stabilizer, said the person familiar with the plane
maker's work.
Engine makers put their engines through a battery of tests to
make sure they will hold together if a fan blade breaks. They are
largely focused on making sure debris doesn't go through the side
of the engine casing, where it could penetrate the body of the
plane. Broken fan blades can still cause damage by flying
forward.
Coverings go through their own certification process on a
separate track.
While engine coverings are expected to contain broken fan
blades, they aren't designed to shield more-serious failures of
hubs the blades are attached to -- as happened on an Airbus A380
jet over Greenland in 2017. Parts fell off at 37,000 feet, damaging
buildings but causing no injuries.
Within about two weeks of that incident, the FAA issued an
emergency order requiring inspections on roughly 120 of the jets
equipped with certain engines produced by Engine Alliance, a joint
venture between GE and Pratt & Whitney. GE referred inquiries
to Pratt & Whitney, which declined to comment on Engine
Alliance's behalf. An Airbus spokesman said the plane maker takes
into account past incidents and accidents, including those on other
manufacturers' aircraft, to enhance safety.
Boeing engineers have been working on a plan to strengthen 737
engine covers, essentially to soften the shock of a fan-blade
failure and keep parts attached to the plane even when the blades
fly forward, people familiar with the work said.
In March 2020, FAA Administrator Steve Dickson told the NTSB the
agency was working with the plane maker to strengthen the 737
engine covers, according to written responses to the NTSB's
recommendations. He said the agency would eventually mandate a new
design change. The FAA declined to make Mr. Dickson available for
an interview.
In August 2020, Boeing provided an update to the FAA on its work
to also strengthen 777 engine covers. The manufacturer told
regulators it had decided to redesign and make replacement covers
with which airlines could retrofit their fleets, according to the
FAA document.
Boeing's 777 engine-cover fix didn't come in time for the Dec. 4
incident near Japan, on a Japan Airlines Co. 777 with Pratt &
Whitney PW4000 engines. Two of an engine's fan blades broke shortly
after takeoff from Okinawa, according to a preliminary report by
Japanese investigators. Part of the engine's cover detached, and
the jet's body and horizontal stabilizer sustained damage, the
report said. A JAL spokesman declined to comment on the cause of
the incident.
The FAA held off ordering immediate action. After the December
incident, the agency said it reviewed the JAL engine's maintenance
and inspection history, conducted a metallurgical exam and was
evaluating whether to adjust blade inspections.
It wasn't immediately clear to investigators and regulators
whether the fan-blade cracks at the root of both 777 engine
breakups roughly two years apart shared the same underlying cause,
according to a person familiar with the FAA's response. Age,
manufacturing defects or maintenance slip-ups can cause metal to
crack and eventually fracture. The FAA declined to comment about
its work with Boeing on 777 engine covers.
Since the Colorado 777 incident, Boeing has shared some of the
changes it is considering to shore up 737 engine covers with
carriers including Southwest and American Airlines Group Inc., said
people briefed on the matter. It has also been in talks with United
about potential changes to 777 engine covers, according to a person
familiar with those discussions. Boeing and the FAA declined to
comment on when 777 or 737 engine-cover fixes would be
completed.
Japanese regulators grounded the aircraft the day after the
Colorado incident. Soon thereafter, Mr. Dickson ordered immediate
specialized inspections even while some FAA officials didn't
believe such drastic action was necessary, said people familiar
with the agency's response.
The move, which the FAA described as "decisive action,"
effectively took more than 50 Boeing 777s with certain Pratt &
Whitney engines -- all operated by United -- out of service for
months, until inspections have been completed.
Tom Haueter, a former NTSB director of aviation safety who now
consults on safety and accident investigations, said: "They
grounded the fleet -- that's about as aggressive as you can
get."
--Chieko Tsuneoka, Benjamin Katz and Doug Cameron contributed to
this article.
Write to Andrew Tangel at Andrew.Tangel@wsj.com and Alison Sider
at alison.sider@wsj.com
(END) Dow Jones Newswires
March 19, 2021 10:19 ET (14:19 GMT)
Copyright (c) 2021 Dow Jones & Company, Inc.
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